The present application relates to an inlet, for example such as used on an auxiliary power unit.
Aircraft auxiliary power units (APU) are gas turbine engines often located in an aircraft empennage, fuselage, wing root or fuselage wheel well area. The APU typically receives inlet airflow through an inlet duct and discharges an exhaust through an exhaust duct.
During various conditions including anti-icing operations, various fluids may enter the APU inlet. If a sufficient quantity of fluid enters the APU inlet, damage to the APU may eventually occur.
A winter inlet louver may be temporarily mounted over the APU inlet. Although effective to protect against overnight snow, the winter inlet louver may not significantly protect from anti-icing fluids. Furthermore, the winter inlet louver often applies a spin or prewhirl to the free stream airflow which may reduce APU performance.